To determine the mechanisms which underlie tissue-specific gene expression in mucin-producing salivary glands, we are studying the expression of the glutamine/glutamic acid-rich promoter genes. We have recently cloned the GRP-Cb gene and are currently sequencing it. This will allow comparison with the promoter region of the GRP-Ca gene. We have also begun gel shift analysis of the promoter region of the GRP-Ca gene. KEY WORDS: Salivary gland-specific gene expression